The inkjet image-drawing device that conducts image-drawing by causing a liquid-drop to impact on a substrate (work) by using an inkjet head is utilized widely for an industrial use such as drawing of a wiring pattern on a semiconductor substrate and a pixel pattern of a color filter in a liquid crystal display device, for example. In the use of this kind, image drawing is conducted generally by using a head unit wherein a long line head is structured by arranging many inkjet heads in a zigzag fashion, for enhancing productivity.
By the way, in the inkjet image-drawing device of this kind, image drawing which is extremely precise and highly accurate is requested. For example, in the image-drawing of wiring pattern of semiconductor substrate, it is necessary to cause a liquid-drop to impact at an accurate position in a micron order without causing a short circuit with adjoining wiring, and it is necessary to cause a liquid-drop in a prescribed color to impact accurately in a prescribed matrix in accuracy of a micron order, in the case of image-drawing of image pattern of a color filter. Therefore, it is necessary for the positional relation between an inkjet head and a substrate and for the position of impact of a liquid-drop to be controlled strictly.
Therefore, there has been known a technology to conduct image recognition for a substrate by cameras, and thereby to conduct positional correction for the substrate and an inkjet head, based on the aforesaid image recognition.
Namely, Patent Document 1 discloses that an alignment optical system for measuring slippage of a substrate for a standard position and a position evaluating optical system for image recognition are provided on the same stage, and these optical systems are used to conduct positional adjustment for the substrate positioned to be lower than the aforesaid optical systems.
Patent Document 2 discloses that an image processing camera is arranged on a frame provided on a stone planometer, and a substrate positioned to be lower than the camera is picked up to correct the position of the substrate. In this device, highly accurate parallel straight lines can be drawn for the substrate, by causing a moving section to be made of stone or of ceramic.
Patent Document 3 discloses that a camera carriage is provided on X-axis direction moving mechanism having a main carriage that supports a head unit, and this camera carriage supports an alignment camera and an image-drawing confirmation camera to conduct position correction of the substrate by picking up the substrate position to be at a lower part.
Patent Document 4 discloses that an alignment camera is provided on a device frame, and a substrate positioned to be lower than the alignment camera is corrected in terms of its position by detecting XY axes coordinates of the substrate. Further, it is disclosed that a camera for detecting a position of impact is provided on a Y axis moving mechanism that is the same as a head.
Patent Document 5 discloses a head unit wherein a line head is structured by arranging many inkjet heads.